Cruck Framing workshop

Heartwood is adding a 5-day Cruck Framing course to its 2016 schedule from May 16–20; the frame will be similar to the one shown below built in 2011. Cruck frames use large “bookmatched” curved timbers to transfer the weight of the roof directly down to the foot of the posts. It is a traditional method found mainly in the Welsh Borderlands in Britain; here in Berkshire County we have more crucks than anywhere else in North America. They are quite beautiful with the arches soaring overhead, and exciting to build as the scribed crucks take shape.
For more information including a video of a previous class,
please visit our website here .
Instructors: Jack Sobon and Neil Godden
We urge you to register as soon as possible
for this course if you are interested.

Is it true, Jack has built so many cruck frames the Berkshires are starting to sink?

Is this a hand tool only workshop or will you also use some power tool?

Tim,
Haven't noticed any cruck creep yet. This cruck frame will be going to Vermont after we raise it at Heartwood, so we're spreading the load around.
All hand tools except for chainsawing. We will axe and hew or adze the curve on one of the cruck pairs and ties and then use a chainsaw jig to cut another pair, just so people can see both methods. The flat sides of the crucks and ties will be pre-sawn by a WoodMizer and then cleaned up with smoothing planes.

Thanks, Will. Perhaps, and evidently, Cruck Creep is horizontal not vertical, as this one is creeping into Vermont.

Have you see how a band saw can cut the inner and outer curves as well? It is tricky coming out of the curve or going into a rise cut, as the leading cutting edge of the band wants to cut straight but with careful attention it can be done on shallow curves. I feel it puts some stress on the band, I use an older band. The surface still needs a little hewing for aesthetic reasons. No jig here, free hand.

https://www.youtube.com/watch?v=I6NBYTBFDgM

Nice! Would probably use it if we had it. No hydraulics on our little LT10, although I might try it with just hand power. However, we also want the folks in the course to know how to do it with their own tools.

Hi Will,

I am trying to get one of my students to take your Cruck Framing course...I hope it works out.

We have cut many curved pieces on our band mill (Oscar 30") and it works great just as Tim has so brilliantly demonstrated. I have also done this on a manual Wood-Mizer, and Timber King.

With the saw running (and being very careful) I recommend "rounding" (an old boat builders trick when doing band saw work) the back edge of the blade. This seems to assist following the curve.

Tim's demonstration was masterful to say the least, I have never been able to move that fast!!. We have done much more pronounced curves, and in all cases, we draw a "cut line" on the timber to be milled and make a very slow effort to "take the line," as we mill. A fat sharpie pen does well for the layout line.

With a little practice, I think you could do just fine with the mill you have.

Thanks Jay,
We'll try a test piece, and since we have three cruck pairs this could be the third method we use in the workshop.
How much would you round the back of a 1.25" blade; maybe taper the back 1/8" on both sides?

Hi Will,

Here is the approach and tools I find most expedient:

1. I gather a Small piece of emery cloth, flat diamond file (coarse), and then a large black or dark blue sharpie pen.

2. With the engine running on idle...I "ink" the back of the blade. This is the "tell marks" often used by Smiths when shaping blades.

3. With the blade now turning just fast enough to engage the diamond file to "cut in," I do so into the top edge of the blade. I oscillate the diamond file on the top edge first from a 15 degree angle down to a 45 degree angle until a rough 45 degree profile is achieved on the top edge of the blade.

4. Repeat all steps thus far on the bottom edge...

5. With a rough "V" chamfer on the back of the blade...(note: this can be shaped in spots!!)...I now round over the "V" chamfer into a rough "bull nose" or "rondel" profile.

6. Smooth with the emery cloth.

The above are the basic stages of approach, and the tools. The dynamics of attempting this will teach better than my words. I thought I had this in a syllabus someplace, yet can find it. Feel free to cut, past, and edit at your leisure this post for the class if that has benefit.

Regards,

j

On my mill I have encountered a burr building up on the back of my band, it doesn't happen often perhaps from a defect in the hardening process the band went through at the factory, and have taken the burr off with a sharpening stone. Yes, with the mill running very similar to Jay's description. I didn't notice the fine print in Jay's post, so I am taking it upon myself to put it out there. Use extreme caution when doing this, need I say more. I have 27 stitches in my little finger alone from getting tangled in my debarker, luckily not the band. My finger still works, it looked like cottage cheese with some pink mixed in at the time.

I do agree the rounded back would help. You can also get narrower bands than 1.25" I have never tired but I may order in a special 3/4" band for such cuts. Maybe less thick, too. It only need to make a few cuts now and again. It should hold up.

I would suggest if anyone wants to try cutting curves on the band try on sample stock first. The idea of this comes from two different directions. One, running a dull band and seeing it dive two inches and then coming back out of the dive while I was not attending the levers, I was off bearing by myself while the band was self feeding. Two, being impatient when sawing, taking a cut and wanting to rise out of the cut befor I get to the end of the log due to a trashy end on the log that will not yield and decent lumber. Oh, a third example, cutting long stock I have been know to start out cutting 2" thick stock and by the mid point or so, drop the cut to 5/4 or 1" for the other half of a 36'cut.

Tim, Jay,
Couldn't the blade be tapered off of the mill, on a bench with a grinder or Dremel? I know it would take longer and maybe not turn out as uniform, but would be a lot safer.

Hi Will...

I have done it on the mill with a Dremel before as well...

As for safer, that is "perhaps," more perception and actuality.

Being several decades into the "Wilderness Risk Managers" committees and "death and accidents in mountaineering groups" there is a running theme among outdoor and adventure professionals called: Perceived Risk vs Actual Risk...

Very often what seems "very risking," like lead rock climbing is comparatively much safer than something like " rappelling." The idea of touching the back of a saw blade may well seem very risky and is not to say that precautions do not have to be taken, as indeed they do. Nevertheless, the risk is actually (relatively speaking) not that much more risky than other methods that would offer only a partially completed task or one not done to full spec.

I do not support anyone taking on a tasks unless they have garnered confidence they can do it safely...Fear/worry is a "mind killer" and would warrant not attempting such a task as we have been discussing. I would further add this is not a "novice task" and would and should only be attempted by someone very accustom to working around large saws, and their operations...Milling in general is very dangerous in many ways comparative to other woodworking tasks...as is much of the Arborist, logging, and related professions...Be safe first...and if you don't feel safe...you're not...

Good luck and let me know if I can be of further service...When I am in the area again this summer, I can stop by and do a few blades just so you have them on hand when/if you chose to try this...

Regards,

j

I agree Jay. I'm comfortable around the mill, especially if behind the blade. Also, when filing my hands would be 10-12" away from the rollers, so the risk seems slight.
Actually, since the mill is in winter storage mode with the blades off, I was more interested in doing it in the shop for convenience now. At any rate, please do stop by Heartwood anytime you're in the area (best to call first).

I will do that (and be sure to call ahead)!! I am trying to get some students into your Cruck class now, so maybe coming with one of them perhaps for a "visit."

This task is super fast "on the mill" and tedious and cumbersome at it very best "off mill." When actually ready to do it (when and/or if) drop me a line and we can revisit everything...

Regards,

j

Suffolk Machine is where I get my bands, they provide a wide selection of bands, and made to any length you need. An option is to fit on a 3/4" new band, as a replacement for the 1-1/4" you run now. I would try that and not round the back of the band, or you could also round the back of the 3/4" band, too. Maybe have more set in the band as well, .090 set.


http://suffolkmachinery.com/

Good point Tim...

I only run 3/4" for this process of cutting curves and have never tried wider blades for it. I have run 1/2" and that may be better, if you can find one...

Do you think "more set" would actually be better?

I have found (sometimes on certain woods) when cutting "free form" on bandmills of all types it is typical to run the narrowest blade width as possible for the machine (and tension set) with "little to no set" in the teeth...This allows the curves and undulations to go in any direction more freely...

Regards,

j

That could be the case. I'm only thinking of giving the band more room to make the curve. I don't know for sure. I wouldn't be surprised to see it make no difference either way. I do know a band with low set is more liable to wave, which jives with what you are seeing.

The narrower band, of course will make a tighter curve.

Tim,
The rollers (blade guides) on my LT10 are wider than a 3/4" blade, I think (I'm not over there now), so when the blade is backed up against the lip on the roller it seems that the teeth (and set) would be hitting the roller, and dulling them
Can you give me the thickness and tooth pattern you get on your 3/4" blade?.
Thanks.

I actually have not run a narrower band on my mill. I do want to try one, though. My guides are stacked R-10 bearings, it normally runs with three stacked, I would remove one for the narrower band. The Lt10 may not be able to do this. I suspect it would take the set out of one side of the band. As for thickness of the band it looks like Timber Wolf has a 3/4" at .032 thickness and 1" band at .035 thick. You would have to spec the length. Looks like they run around $27 for a 13'er.

Great information Tim...

I haven't run an Lt10 (15?) since about 98 or so...I do believe then they had to modify the bearing assembly to do something like what we are discussing here...

I am not fond of the larger "cantilevered heads" on mills, and is part of the reason I have always bought and recommended Hudson products over others...(which isn't an issue with smaller Mizers) It's kind'a like the "Apple vs Intel" stuff in the "computer geek" world however and not really a reflection on the machines themselves...per se.

If someone is just a "user" and needs a general mill that "does a task of milling" and doesn't ask for much other than operating within those parameters the Wood Mizer, is a good machine...It will do the jobs asked of it...(aka Apple.) Just like I know many (not all) graphic designers "LOVE...!!...Apple computers"...PE (and those that work closely with them)...tend to like "Intel" computers and/or building custom "motherboard/graphic card" configurations...

If one is a "tinkering Geek" and always "asking more" of a machine and/or "modifying and updating" their machines to do other tasks...then a "nonproprietary machine" like the "Oscar" line from Hudson is a much better offer price and operating parameter wise... The differences between that orange paint compared to "red," seems rather significant for what one gets between these two mill companies...(ha ha... )

If will can get on a narrow bearing as recommended that "should" (??) do the trick...

The manufacturer of my mill, now no longer in production, did R & D for Woodmizer, the result was the Lt 10 and 15 units. He also made a version to function in the depths of Russia in severe cold temps. I don't recall the details but the hydraulic system was minimal due to the cold temps. It was similar to the mill I use but larger. All my parts can be had without going through a specific manufacturer, standard parts sourced through various companies.

I would like to give one of the canted head mills some time. I can see some advantages. Or a swing circ saw. All and all I am happy with the unit I run. I'm considering an electric servo unit to engage the throttle, the cable system was alway stiff and it finally seized so I'm running a bungee cord on the throttle, for now.

Tim, if you ever get a chance to try one of the larger (250 mm of larger) swing blades...take advantage of the experience. I don't think you would be disappointed...Both systems have there advantages...together they more than facilitate small lumber operations...Now have used and owned both...if $$$ allows (swings are more money up front)...and only could have one mill...it would be a swing mill...

Here's an updated drawing of the 16' x 20' cruck frame we will be doing in our May 16–20 workshop:

There is still room in the course!

Thanks for sharing the drawing.

I'll see you on Thursday (that week).

Jim Rogers